Aryloxypropanolamines (1) and arylethanolamines (2) are widely used therapeutic agents, particularly those compounds possessing potent beta-adrenergic receptor blocking activity. These beta-adrenergic blocking agents are widely used for a number of cardiovascular therapeutic indications, such as hypertension, angina pectoris, cardiac arrhythmias, myocardial infarction and more recently in the treatment of glaucoma. In addition, certain aryloxypropanolamines possess potent beta-adrenergic stimulating properties and such compounds are used as cardiac stimulants.
Among beta-blocker oxypropanolamines, the R isomers are less active or essentially devoid of beta-blocking activity as compared to their counterpart S isomers. Similarly, the R-isomer beta-agonists are more potent agents than their S-isomer counterparts. ##STR2##
Conventional methods for preparing such compounds utilize the hydrolysis of the ketal 3 to give the diol 4 followed by the HBr/AcOH treatment to provide the bromoacetoxy 5. Subsequently, the bromoacetoxy 5 is transformed into an epoxide which is then treated with the corresponding amine to provide the desired beta-blocker in separate stages. Such a procedure is described by S. Iriuchijima and N. Kojima, Agric. Biol. Chem. 46 (5), 1153 (1982). In such a procedure, to prepare the optically active aryloxypropanolamines, four steps are required, starting from the ketal 3. An efficient and an economical process for preparing the separate isomers is therefore highly desirable. ##STR3##